From: Christoph Hellwig <hch@infradead.org>
To: Theodore Tso <tytso@mit.edu>
Cc: Christoph Hellwig <hch@infradead.org>,
Cyber_black <Cyberblackk@proton.me>,
"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
Mark Fasheh <mark@fasheh.com>,
linux-api@vger.kernel.org
Subject: Re: [RFC] fs/ioctl.c: FIBMAP requires CAP_SYS_RAWIO while FIEMAP exposes identical data unprivileged
Date: Tue, 19 May 2026 04:42:09 -0700 [thread overview]
Message-ID: <agxMkaEMMbQGzqsk@infradead.org> (raw)
In-Reply-To: <20260519022327.GA11894@macsyma-wired.lan>
On Mon, May 18, 2026 at 10:23:27PM -0400, Theodore Tso wrote:
> I disagree. As I recall, we discussed whether or not FIEMAP needed to
> be unprivileged many years ago, and it was a conscious choice not to
> require root privs. I don't believe it is a security issue to allow
> users to see the logical -> physical block mappings for inodes.
Users have no business even known it. It is a side channel that can
easily leak information for attackers that know allocation policies.
And as the reported state it also is inconsistent with how FIBMAP has
behaved since the damn of time.
prev parent reply other threads:[~2026-05-19 11:42 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <_fcorj7Aa0YnzUmrPnqdEbTjLqS6S7t84HKrzsswvKm71LC0uVmTD2cthCwpgeI-296unEpzPZYBNdFFDXjsQvZRtGfTaQlKmcRkiSI4wiQ=@proton.me>
2026-05-18 5:08 ` [RFC] fs/ioctl.c: FIBMAP requires CAP_SYS_RAWIO while FIEMAP exposes identical data unprivileged Christoph Hellwig
2026-05-18 16:20 ` Darrick J. Wong
2026-05-18 16:22 ` Andy Lutomirski
2026-05-19 3:31 ` Darrick J. Wong
2026-05-19 7:53 ` Andreas Dilger
2026-05-19 11:45 ` Christoph Hellwig
2026-05-19 20:51 ` Andy Lutomirski
2026-05-19 2:23 ` Theodore Tso
2026-05-19 11:42 ` Christoph Hellwig [this message]
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